机械喷丸对X80管线钢疲劳性能的影响

Effect of mechanical shot peening on fatigue property of X80 pipe steel

为了研究机械喷丸对X80管线钢疲劳性能的影响,利用气动式喷丸机对X80管线钢试样进行机械喷丸处理,对机械喷丸前后单联中心孔试样小孔两侧残余应力分布进行测试,探讨机械喷丸时间对X80管线钢疲劳寿命的影响,分析机械喷丸前后单联中心孔试样疲劳断口形貌。试验结果表明:机械喷丸后,X80管线钢表层分布高幅值残余压应力,表层残余压应力分布显著降低了疲劳裂纹扩展速率,疲劳寿命明显提高;通过扫描疲劳断口,发现未喷丸处理试样的疲劳裂纹源位于孔壁上表面的尖角处,而机械喷丸试样的裂纹源逐渐转移到强化层以内。在疲劳裂纹稳定扩展区,疲劳条带间距随着机械喷丸时间的增加而减小,说明机械喷丸有效降低了管线钢疲劳裂纹扩展速率,改善了X80管线钢的疲劳特性。

In order to identify the effect of mechanical shot peening on fatigue property of X80 pipe steel, the pneumatic type shot peening machine is used to treat the X80 pipe steel sample, and residual stress distribution on both sides of the holes of single-linkage central hole sample before and after mechanical shot peening is tested. Then, the effect of mechanical shot peening time on the fatigue life of X80 pipe steel is discussed, and the fatigue fracture morphology of single-leakage central hole sample before and after mechanical shot peening is analyzed. The test results show that high magnitude compressive residual stresses are distributed on the surface of X80 pipe steel, which reduce the growth rate of fatigue crack significantly, and the fatigue life has improved obviously. Through scanning the fatigue fracture, fatigue crack source of the sample without shot peening is found at the corners of the upper surface of the hole wall, and the crack source of the sample within mechanical shot peening is gradually shifted into the strengthening layer. In the stable extension area of fatigue crack, fatigue banding spacing decreases with the increase of mechanical shot peening time. It shows that mechanical shot peening effectively reduces the fatigue crack growth rate of pipe steel and the fatigue property of X80 pipe steel is improved.